Safety attachment for aircraft



3 1927. T. DOUGLAS SAFETY ATTACHMENT FOR AIRCRAFT Filed Jan. 24. 1919 2Sheets-Sheet 1 INVENTOR Theodore Doqg BY WM ATTORNEY May 3,1927.1,626,921

"r. DOUGLAS SAFETY ATTACHMENT FOR AIRCRAFT Filed Jan. 24. 1919 2Sheets-Sheet 2 ads Mon 275420 We floaylas.

Patented May 3, 1927. p p

UNITED STATES PATENT OFFICE.

THEODORE DOUGLAS, OF SCARBORO, NEW YORK, ASSIGNOR TO DUPLEX ENGINEGOVERNOR COMPANY, INC, OF BROOKLYN, NEW YORK, A CORPORATION OF NEW YORK.

SAFETY ATTACHMENT FOR AIRCRAFT.

Application filed January 24, 1919. Serial No. 272,958.

The invention herein set forth relates to an attachment foraircraftg'and aims to provide an instrument which can be combined withthe power system embracing the engine of the airship in such a way that,whenever a shock involving the engine occurs. the operation of thelatter is interrupted at once by the automatic suspending of theoperation of the ignition system supplying electrical current to thecylinders of the engine to produce combustion of the fuel therein.

My invention is designed for airships with one or more engines, and iscapable of acting in case of emergency, to affect and ,control theignition system by either open-circuiting or short-circuiting the same,thereby afiording the attainment of the desired end.

An object of my invention is to provide an attachment which will besimple in construction and capable of being easily applied and connectedin operative relation so that it will instantly and infallibly takeeffect under predetermined conditions to avert serious consequencesbefore the aviator can take measures by hand to insure his own safetyand the safety of his machine.

It very ofteri happens when an aviator is making a flight that apropeller blade breaks or something else happens; making the engineimmediately become unbalanced and wrench itself loose from itsanchorage. Frequently in such cases the gasoline line is broken, andfire has been known to start as a consequence of the continued sparkingin the engine cylinders and the flaming exhaust into the atmospherebefore the aviator has time to manipulate the main switch of theignition circuit; even when such switch is easily within his reach.Under such circumstances the engine may not only tear itself from itsfastenings, but even go overboard before the aviator can fully realizewhat has come to pass; and when fire due to the escape of gasolinecommences, the end ofboth flier and flying machine may follow.

Such breakag-es are infrequent under ordinary conditions, but likely tohappen, from gunfire and accidentally, in war. In an 0 aerialengagement, the objective is to put either the hostile flier or hismachine out of commission; therefore the pilot and the machine carryinghim are the important targets. Now, when an aviator is in action hemachine, he necessarily sacrifices altitude;

which is priceless and generally determines whether he can get back overthe enemys barrage into his own territory.

My invention eliminates the danger from accidents such as I have justoutlined by mechanism which is quite simple, involving relatively fewparts and comprising no eon struction which is bulky, complicated orexpensive; and which can be mounted upon an airship so that it willinstantly respond to an abnormal vibration or other bodily movement ofthe engine driving the same, in order to cut off the flow of ignitioncurrent to the spark plugs and cause the engine to stop developingpower. In this way, in case a propeller blade should break, or somethingelse should happen to unbalance the engine, the danger of the lattertearing itself loose and causing a destructive fire is fully obviated.Hence the instrument does not in any way interfere with the airship buton the contrary is of great utility; making the pilot free for his fightwith the enemy and enabling him to sail about and maneuver aloft incomplete confidence.

Other objects and advantages of my invention will more clearly appearfrom the following description, taken in connection with theaccompanyine drawings forming a part of the same; and thecharacteristics of my invention will be precisely defined in theappended claims. This disclosure, however, is explanatory only, and Ireserve the right to adopt embodiments of my invention other than whatis actually shown herein to the full extent indicated by the generalmeanings of the terms in which the claims are expressed.

On the drawings Figures 1 and 2 are top and bottom views of the casingof an instrument according to my invention; 7

Figure 3 is a view of said casing and con tents, without the cover;

Figure 4 is asection on line 4.4, Figure 3;

Figure 5 is a bottom plan of the cover of i this instrument;

Figure 6 shows diagrammatically circuit connections therefor;illustrating the manner in which the invention is'comhined with theignition system;

Figures 7, 8 and 9 are top. bottom and end views of a switch for theinstrument;

Figures 10 and 11 show top and bottom views of the casing of a modifiedform of instrument Figure 12 is a view thereof, similar to Figure 3;

Figure 13 is a section through Figure 12 similar to Figure 4;

Figure 14 is a bottom of this modification; and

Figure 15 shows a diagram of the circuits for same.

The invention described hereinafter is an improvement upon a similarinvention set forth in my copending application, Serial Number 209,130,filed December 27, 1917.

The same numerals identify the same parts throughout.

Referring to the first two figures on the drawings, I show one form ofmy safety attachment for the power system of an airship as a Whole at 8.The arrangement of the parts of this attachment is such that, as I shallset forth fully hereinafter, the attachment will automatically cut offthe ignition current by open-circuiting the ignition system and it isadapted to be operated by any abnormal bodily movement of the engine, aswhen there is an unbalanced condition resulting from a broken propellerblade. In that event the torque of the engine, which would be normallydivided by the blades and thus produce a balanced load, is then nolonger properly divided; producing a badly unbalanced load, and jerkingor pushing the engine from side to side as the propeller revolves. Undersuch circumstances a tractor plane is liable to go into a dive; a pusherplane into a tail stall; and either is apt to pass next into atail-spin, and the engine may or may not go overboard entirely. If thisside pressure does become so great that the engine is broken from itsfoundation and thrown out of the airship, the center of gravity of themachine is upset, completely destroying its equilibrium, and effectingother and more serious damage. The attachment 8 produces a suspension ofthe operation of the ignition system to stop the engine chiefly throughthe instrumentality of an element such as a pivotally mounted bar 11,comprised in the attachment 8, and housed in a casing 12. See Figure 3.This bar has sufiicient mass, and it is supported upon its pivot 13 inthe easing 12, so that it can move or swing or us cillate, like apendulum, in a direction that extends across or transversely of thelongi tudinal axis of the engine; that is the bar should preferablyswing parallel to the plan of the cover plane of the propeller. I maysecure the attachment 8 to any part of the aeroplane so related to theengine that any transverse jar will instantly be transmitted to the bar11 hence I can mount the attachment either upon some part of the engineframework directly, or upon a part of the aeroplane or other airshiprigid with it. such as the instrument board in the pit of the fuselage;or near enough to it to be subject to its vibration, such as one of theengine hearers when in the wings. Preferably the casing 12 and bar 11are both in vertical position, and the bar, to stop the engine, swingsin a direction transverse to the crankshaft thereof. I may also mountthecasing 12 so that it will be horizontal and the bar 11 will normally lieparallel to the crankshaft. However, the car 11 will still be inposition to swing in a direction transverse to the crankshaft, and theattachment can therefore perform is function when needed quite as easilyas in the first instance, to respond to a transverse shock from theengine as a result of its unbalanced torque reaction.

The casing 12 and parts borne thereby are illustrated, particularly inFigures 3 and 4. It comprises sides and ends; to which is secured abottom and a removable cover 21. The sides, ends, bottom and cover ofthe casing are preferably of some insulating substance, such as fibre orrubber. To the bottom 20, near the upper end of the casing is fixed aninverted metal yoke 22 in which is carried the pivot pin 13 whereon thebar 11 is hung. As will appear presently, whenever the bar or element 11is constrained to swing sidewise, it acts very promptly in the requiredmanner.

On the outside of bottom 20 of the casing 12 are located four electricalterminals orbinding posts 25; extending into the casing and each joinedto a conductor 73. These binding posts enable the instrument to beconnected into the ignition system and the conductors lead to the partsin the casing that are embraced in the circuit or circuits of same.

At a distance from the pivot 13 to one side of the bar 11 is acompression spring 42". Thefree end of the bar 11 carries a pin orhandle 45 which projects through a slot in the adjacent end of thecasing; and to this pin are secured two other springs 46, one at eachside. The spring 42 and the springs 46 separately constitute means fordamping the oscillations of the bar, and prevent it from functioningunder ordinary conditions. These springs, especially the springs 46,also serve to restore the bar 11 to neutral position after movement ofsame. I oin the opposite ends of the springs 46 to adjustable nuts 50,each of which is movable in the bore of a boss 49. The bosses 49 are atopposite sides of the casing 12. By manipuletting the nuts the bar 11can be moved to exact central position; audit will so remain untiloccasion requires it to swing away from central position. The springs46, with the nuts 50* thus serve also as means for adjusting the bar 11in addition to damping it, and by means of the nuts 50', the tension ofthe springs 46 can be changed as desired.

The spring 42 is carried at one side of the casing near the springs 46,upon a. screw 67 in a threaded bearing 68, in the side wall of thecasing. This bearing is situated in a threaded boss 69, closed by a nut70, in the bore 71 of this boss. A kerf in the screw 67 permits turningthe screw from the outside of the casing by a tool when the nut isremoved.

Each spring 46 is attached to a plug 72 projecting through the adjacentnut 50, which engages threads inside the boss 49. These nuts receiveheads on the plugs 72 and the nuts can be shaped in any suitable way tobe turned by a tool or other device, from without the casingand regulatethe springs 46. Closures for the outer ends of the bosses 49 may beprovided.

At the right, inside the casing, are two conductors 73, each leading toan element 23 on the bottom 20, mounting a pivoted element 74, extendingover bar 11 and carrying a, shoulder 36 to engage a dog 75 on arotatable spindle 76 at the left. Each spindle 76 has an arm 77, securedto a tension-spring 78 anchored in a recess in the bottom of casing. 12.These springs force the dogs 75 against the shoulders 36. Other elements23 on the bottom 20 mount the spindle 76 and are connected to similarconductors 73 in the casing 12. All conductors 7 3 are joined to bindingposts 25 on the back of the casing. Each element 74 has a cam face 79and the bar 11 carries round-ended steel screws 80 to engage the camfaces 79.

A transverse shock causes the bar 11 to move the elements 74 upward,releasing the dogs 75. To free these dogs 75 simultaneously I place thescrew 80 which is nearer to the pivot 13, so as to be adjacent the leftside of the bar, and the other screw 80 at the right side. The bar isrecessed at 81 adjacent the latter screw to give the adjacent cam face79 sufiicient clearance till this other screw strikes it.

This instrument is for engines havingtwo distributors and is connectedso that" each element 74 is joined in series with the main circuits ofthe ignition system. Figure 6. In this view two electrical generators,such as batteries or magnetos are shown at 82. Each is in series throughsuitable conductors with one of the elements or triggers 74; and fromthe attachment 8 the current from those generators passes to suitabletranslating devices 83, which may rep resent distributers. Thesedistributers supply high tension current to the spark plugs of theengine by turns, the current from each generator being stepped up beforeit passes through the-distributer by suitable means, such as atransformer, or induction coil. The engine will have two sets ofigniters, one set supplied from one generator and distributer and theother set by the remaining distributer and generator. Hence eachcylinder of the engine will have two spark plugs and both sets ofigniters may be used together, or only 'one at a time, with one of thegenerators and distributers, may be in service; the other set, with theremaining generator and distributer, being kept in re serve, as anauxiliary or relay, to be thrown in if the first set fails or ceases toWork properly. A shock will open the circuits of both generators anddistributors at once.

The bar 11 is insulated, and elements 23 and 74, the dogs 75 and thespindles 76 conductive. I

My invention is of course useful on pusher planes as well as tractorplanes; and ondirigible balloons; because when a propel ler on a balloonbreaks, fragments may puncture the gas bag and liberate the inflammablecontents.

When an accident happens the flier hardly ever has time to do anythingto save him self, even if he remains calm and uninjured. With theattachment 8, ignition is automatically terminated within a fraction ofa revolution of a high-powered. engine; and if gasoline is spilled, firedoes not ensue.

Casing 12 may also be placed parallel to the wings if the bar 11 isarranged to swing transversely of the engine.

The force of the springs on each side of the bar 11 is of courseadjusted to make the attachment 8 inoperative Within the limits of thesafe operation of the engine; causing the pendulum bar to remain neutraluntil that limit is exceeded.

It sometimes happens too that when an aviator is making a flight anaccident may happen in some other manner than by the breaking of apropeller blade, and may cause a shock to the engine that is more orless parallel to the axis of the crankshaft instead of transverse to thesame. Such a situation may result from a collision. If it is desired toguard against such athing, the attachment 8 can be mounted so that thecasing 12 willhave its top 21 and bottom 20 parallel with the crankshaftof the engine. and with the bar in vertical or horizontal position, buttransverse to the crankshaft of the same. With this arrangement acollision producing a substantially longitudinal shock will cause thebar to swing in a plane that is more or less parallel with the enginemishap of both kinds; that is, anything that might produce a transverseshock to the englue or a longitudinal shock also; I may use two of myattachments 8 with the same engine, by mounting one so that the bar willbe able to swing in a direction transverse to the crankshaft and theother so that the bar can swing in a direction that is more or lessparallel with the crankshaft. The two instruments may both be arran ed,for example, so as to suspend the ignition, whichever one takes effect,by connecting the two instruments in series with each other; that is tosay, simply by adding another instru ment to the one shown in Figure 6,and connectingit in circuit with the generators, etc., in the same way.Then in case of a collision, whichever of the two instruments allows itspendulum bar to swing in a direction parallel to the crankshaft willcause the opencircuiting of the ignition system; and in case a shockoccurs transversely of the engine, the other one will produce therequired effect. With two attachments on an aeroplane, the ignition canbe interrupted in case of an accident that is caused by practically anyshock to the aeroplane substantially parallel to the plane of the wings,whether longitudinal or transverse, or even in a diagonal direction;although the mode of operation will be best and surest of course whenthe shock is either directly transverse or directly along the length ofthe engine.

The spindles 76 also each have an arm 84, beneath a projection 85 on aplunger 38 in the cover 21. After the dogs are released, the pressing ofthis plunger, through the arms 84, turns the spindles 76 to reengage thedogs with the shoulders 36. A spring 10 engages the head of the-plungerand the cover to force the plunger normally outward with respect to thecasing.

The spindles 76 also have arms 86, one on each spindle, which pressagainst slide members 87; said members being in grooves, not shown, onthe inner face of the cover 21, be neath openings 88 therein; andengaged by springs 89 upon projections carried by strips 90. See Figures4 and 5. When the elements 74 hold the dogs 75, the arms 86 force themembers 87 to keep cross-marks thereon out of registry with openings 88.These marks come into registry ,with the openings 88, when the elements74 release the dogs. By luminous paint these marks may be made visibleat night and they tell whether or not the instrument is ready. Thestrips 90 retain the members 87 in place on the inner face of the coverand have slots to receive downturned ends of the members 87. abuttingthe springs 89. (Figure 5.) The projections on these strips engaging thesprings 89 are at the opposite ends of the slots, and the downturnedends of the members 87 can move freely in these slots, as will beunderstood.

In Figure 1, the cross marks appear. But with the elements 74 and dogs75 as in Figure 4, the marks will not be visible.

Figures 7, 8 and 9 show a switch comprising insulation 91 carrying twoconductive members 92, between which are two pairs of spring contacts93, one pair at each side.

The contacts at the left are joined to binding posts'25 at the left, bystrips and screws passing through the insulation 91. (Flgure 8.) Thecontacts at the right are disconnected. Bearing members 92 are joined byscrews and strips on the bottom of the insulation 91 to the bindingposts 25 at the right; and support a handle 94 of insulation, carryingseparated metallic strips 95 having trunnions 96, to pivot it. Thisswitch is to be in multiple with the instrument 8 (Figure 6), the twoupper posts being connected in the line of one generator 82, and theremaining posts in the line of the other. With handle 94 to the right(Figure 7) the two upper posts are bridged, likewise the two lowerposts, and the instrument is shunted out. lVhen thrown to the left theswitch moves the metallic strips 95 upon the contact springs 98, at theright, and the binding posts will be disconnected, throwing theinstrument in. Stops 97 on the. members 92, limit the throw of theswitch. This switch in some cases can be mounted directly on the cover21. 1

Figures 10 to 15 inclusive illustrate a modification having a singlecatch 34 over the bar 11, engaging a single dog 7 5 on a single spindle76 in the casing 12. On the back of the casing are right and leftbinding posts 25, connected to conductors 73 on the inside of thecasing. One of these conductors extends to and is electrically connected with a contact element 98, secured to the bottom of the casing12, and having a projection 99, hearing against the spindle 76. Theother conductor 73 leads to a contact element 100, fast under theelement 23 which supports the spindle 70. This element has a projection101 bent towards the dog 75. Below this projection is another contactelement 102 to be grounded through a third conductor 73. lVhenever thedog 75 is liberated it presses the projection 101 upon the terminal 102,grounding both conductors 73, connected to the right and left posts 25.

The terminal 102 joined to an element 103 on the bottom of the casing incircuit with the element 104 carried by the cover 21. A switch on theouter face of the cover 21 comprises springs 93, the left spring beingconnected to the element 10 i and the other spring at the right beingdead. See Figures 10 and 13. The handle 94, of insulation, has a metalinset 95 to engage the springs 93. A pivot or trunnion on the handleengages the member 92 and connects electrically with the metal inset 95.One member 92 is insulated; the other is in circuit through a metalstrip 105 on the cover 21 with the third conductor 73, and third bindingpost 25 on the back of the bottom of the casing. When the switch isthrown to the right, the elements 104 and 105 will be connected, anddisconnected when the switch is thrown to the left. Figure 15 shows thediagram of circuits. This instrument is for engines with two ignitioncircuits, supplied with ignition current from two magnetos 3; andgrounds both magnetos through the post 25 One magneto serves for onecircuit and the other for the remaining circuit and as many spark plugswill be connected to each magneto as there are cylinders to the engineassociated therewith. The spark plugs may be utilized as before withboth magnetos, both circuit and all the plugs in service at once; oronly'one ignition circuit with one magneto and one set of plugs may beactive, the other circuit with its plugs and magneto being in reserve.These spark plugs are indicated diagrammatically at 2. This instrumenttoo may be made up with the switch separate.

Both the above-described instruments have springs 41 engaging parts 74and 34", and surrounding stems passing through holesin these parts andreceiving the adjusting nuts 107 to regulate the springs.

Both instruments can be employed on not only airships having one enginewith two ignition circuits, but also twin-engined machines; with twopropellers; as an accident to one engine would cause the other to swingthe plane around into a dive and perhaps into a tail spin. Thisusefulness for twinengined machines is especially the case with theinstrument shown in Figures 1 to 5 inclusive. On a twin-engined machinethere will be two such instruments, one associated with each engine; andthe wiring must be such that each instrument must be included in theignition circuit or circuits of both engines. Then the breaking of apropeller driven by either engine will result in actuating the bar 11 ofthe instrument associated therewith; and the ignition circuits of boththat engine and its mate will be afiected instantly. Hence both engineswill be immediatelymade to cease developing power simultaneously. Aswitch like that shown in Figures 7, 8 and 9 will be arranged to shuntout both instruments when desired. After a mishap, the pilot can cut outthe two instruments-and land with dead engines, or switch on hisundamaged engine and continue with it at reduced speed.

When the cover in Figure 14 is applied, the element 103 may be connectedto element 104 and the element 105 to the third conductor 7 3 by metalscrews passing through metallic bosses in the cover into metallicsockets in the bottom casing. Additional screws, bosses and sockets maybe employed to hold the cover on the casing, both in this modificationand the preceding. (Figure 1 above openings 88 and Figure 14 at the endsof the switch.)

The casing for both instruments is shown of insulation, but may be ofmetal with an insulating cover, and a bottom insulated from the sides.The instrument last shown in Figures 10 to 14 inclusive may also be usedto guard against transverse shock or collision, or both. In view. of apropeller blade breaking, the bar 11 will be arranged as before to swingtransversely of the airship; and longitudinally in case of a collision.To guard against both kinds of accident two instruments shown in Figures10 to 14 inclusive are put in parallel with each other and with theignition circuit, one being mounted to let the bar swing transverselyand the other longitudinally of the engine, as set forth above.

Springs 46 and 42 prevent operation of the bar 11 to suspend ignition,from misfiring or shocks in landing. The instrument does not interferewith the ignition.

When there is one engine and the engine and propeller are on thefuselage, the instrument is placed in the pit or on the in strumentboard; with the switch directly on the casing 12. When there are twoengines and each engine is mounted in the wings of an aeroplane, theinstrument is placed preferably on one of the engine bearers, in aweather proof covering. The

switch is then mounted in the pit.

The outer end of the plunger 36 and switch handle may also be touchedwith luminous paint.

To test these instruments before flying, one starts the engine and movesthe bar 11 by the handle 45 to the left till the cross marks appear atthe opening or openings 88.

Before the engine stops the instrument is reset by pressure on theplunger 38, till the marks disappear again. Either of these twoinstruments, can be used also on an engine having a single ignitioncircuit and one set of spark plugs.

My invention may be used on prime movers other than gas engines, ifprovided with electric circuits essential to'regular operation. 1

The types of instruments shown in Figures 1 to 5 inclusive, and Figures10 to 14 inclusive are alike in their main characteristics. Eachcomprises a bar or element 11 for affecting an electric ignitioncircuit, either by breaking it or grounding same;

and in each there are parts of said circuit, preferably inside thecasing, associated with the bar 11. In neither is the bar 11 part of thecircuit. In Figures 1 to 11 inclusive the conducting means in the casingcomprises parts 73, 23, 7 1, 75 and 76; and in Figures 10 to 14inclusive, 73, 98, 76, 75, 100 and 102. Both forms include the means 45for testing purposes, and the plunger or plungers serving as means toreturn the spindle or spindles 76, and enable the ignition system toresume operation.

The spring 42 is chiefly useful as means for desynchronizing; that is,if the bar 11 should oscillate in unison with the ordinary vibrations ofthe engine, the spring 42 will revent these oscillations from causingthe ar to stop the engine under ordinary conditions when no accident hashappened.

Screws 80 can be adjusted from the lower side of the bar 11 to fix thepoint at which the elements 3 1 and 74 will be engaged and made torelease the dogs 75.

Having described my invention what I believe to be new and desire tosecure and protect by Letters Patent of the United States is 1. Thecombination of an element mounted to be movable in response to a shock,a pair of springs engaging said element, means for adjusting saidsprings, and a third spring adjustably mounted adjacent said element toprevent operation thereof except under predetermined conditions.

2. Mechanism comprising a casing, a pair of conductors leading into saidcasing, a pair of conductors leading out of said casing, elements forelectrically connecting said conductors, a pair of spindles having dogsengaged by said elements, an element in the casing mounted to move inresponse to a shock to actuate said first-named elements to release saiddogs, indicating members carried by the casing and visible from theoutside of same, arms on said spindles to control the position to saidmembers, a second arm on each spindle and a plunger for engaglng saidsecond arms to turn the spindles and restore said dogs to engagementwith said pivoted elements.

3. The combination of a pair of contact elements, a dog to press thesame into engagement, a catch for holding the dog out of operativeposition, and an element to be moved by a shock to release said catch.

4. The combination of a casing, a con doctor in same, a spindle carryinga dog connected to said conductor, a contact element in circuit withsaid spindle, a seond conductor connected to said element, anothercontact element adjacent said first named contact element, a pivotedelement engaging said dog, a pivotally mounted bar to move the pivotedelement to release the dog, whereby the dog will cause the contactelements to engage, an electrical conductor connected to said seondcontact element, an arm on said spindle and an indicating membercontrolled by said arm.

5. The combination of a casing having an opening, amember bearing anindication, a spring engaging said member to move the indication intoregistry with said opening, a spindle having an arm engaging said member to keep said indication out of register with said opening, a dog onthe spindle, an element to engage the dog, and a spring to move thespindle to release said member when the dog is disengaged from saidelement.

6. The combination of a casing having an opening, a member bearing anindication, a spring to engage said member to move the indication intoregistry with the opening, a spindle having an arm engaging said memberto keep same out of indicating position, a dog on the spindle, anelement to engage the dog, a spring to move the spindle to release saidmember when the dog is disengaged from said element, another arm on thespindle and a plunger to engage said arm and return the spindle, thedog, and the member.

7. The combination of a pair of contact elements, a spindle, a dogthereon, an element to engage and release the dog, and a spring to causethe spindle to rotate the dog when released to make said contactsdisengage each other.

8. The combination of 'a pair of contact elements, a spindle, a dogthereon, an element to engage and release the dog, a spring to cause thespindle to rotate the dog when released to make the contacts disengageeach other, an arm on the spindle and a plunger to engage the arm andmake the element and dog reengage each other.

9. The combination of a pair of spring contact elements, a releasabledog to move said elements into engagement, a member, and an arm movablewith said dog to permit said member to assume an indicating positionwhen said elements are in engagement, a second arm movable with the dog,and a plunger to engage said second arm to return the dog and saidmember.

In testimony whereof, I have signed my name to this specification this17th day of January, 1919.

THEODORE DOUGLAS.

